KR102563804B1 - Polyester film and packaging material - Google Patents

Abstract

The polyester film of the present invention comprises a first layer containing lactic acid residues; And a second layer containing terephthalate residues and adipic acid residues; a polyester film comprising a layered body alternately laminated, wherein the polyester film was subjected to a rotation of 180 degrees at 800 rpm for 30 seconds or more in film noise level evaluation. It has characteristics such as an average equivalent noise level of 78 dB or less and a Young's modulus of 280 kgf/mm2 or less. The polyester film exhibits excellent flexibility, improves noise performance, and has properties capable of securing transparency.

Description

Polyester film and packing material {POLYESTER FILM AND PACKAGING MATERIAL}

An embodiment relates to a multilayer polyester film with improved noise level. The present invention relates to a packaging material to which a biodegradable polyester film with improved noise level is applied.

Polylactide resin is known as a reusable eco-friendly material that is biodegradable in a relatively short period of time and leaves almost no harmful components.

However, when processed and used in the form of a film, such a polylactide resin generates very loud noise, which has been a limitation in commercialization.

In order to compensate for the disadvantages of these polylactide resins, there is a method of imparting flexibility to the film by blending polylactic acid with aliphatic-aromatic co-polyester, but in this case, low compatibility between polylactic acid and aliphatic-aromatic co-polyester Due to such factors, the transparency of the final film was significantly reduced, making it difficult to use it for packaging applications requiring transparency.

The foregoing background art is technical information that the inventor possessed for derivation of the present invention or acquired during the derivation process of the present invention, and cannot necessarily be said to be known art disclosed to the general public prior to filing the present invention.

Korean Patent Registration No. 10-0904144 Korean Patent Registration No. 10-2404216

An object of the embodiment is to provide a polyester film having improved noise properties, ensuring transparency, and having biodegradable properties. An object of embodiments is to provide a packaging material comprising the polyester film.

One embodiment for achieving the above object is a first layer comprising a lactic acid residue; And a second layer containing terephthalate residues and adipic acid residues; to provide a polyester film comprising a laminated body alternately laminated.

The polyester film of the embodiment has an average equivalent noise level of 78 dB or less in evaluation of film noise level in which rotation of 180 degrees is applied at 800 rpm for 30 seconds or more.

The Young's modulus of the polyester film of the embodiment may be 280 kgf/mm 2 or less.

The polyester film of the embodiment may have a noise level of 63 dB or less at 250 Hz in the film noise level evaluation when the laminate has a thickness of 16 μm.

The laminate may have a haze of 10% or less.

The polyester film of the embodiment may have a haze of 10% or less.

The polyester film of the embodiment may have a noise level of 53 dB or less at 500 Hz in the film noise level evaluation when the laminate has a thickness of 16 μm.

In the laminate, 30 or more layers of the first layer and the second layer may be alternately stacked.

The first layer may further include a hydroxyalkanoate residue.

The first layer may include 1 to 7 parts by weight of the hydroxyalkanoate residue based on 100 parts by weight of the lactic acid residue.

The second layer may include a polybutylene adipate co-terephthalide resin.

The thickness ratio of the first layer and the second layer may be 1:0.2 to 1.5.

The polyester film of the embodiment may further include a skin layer.

The skin layer may be disposed on one side and the other side of the laminate, respectively.

The skin layer may include a first resin containing lactic acid residue; and inorganic particles.

The polyester film of the embodiment comprises a first layer comprising lactic acid residues; and a second layer including terephthalate residues and adipic acid residues; wherein the polyester film is rotated at 180 degrees at 800 rpm for 30 seconds or more to evaluate film noise level. , the noise level at 250 Hz, 500 Hz, 1000 Hz, 2000 Hz, 4000 Hz and 8000 Hz may all be less than 80 dB.

Another embodiment for achieving the above object provides a packaging material comprising the polyester film described above.

The packaging material may be a food packaging material or a disposable product packaging material.

Embodiments may provide a polyester film and the like having biodegradability and reduced noise generation. Embodiments may provide a polyester film that is environmentally friendly, relatively transparent, and has mechanical strength and flexibility of an appropriate level or higher, and a packaging material using the same, while suppressing noise generation in the human audible range, particularly in the low-pitched sound region.

1, 2a and 2b are conceptual views illustrating an example of a polyester film according to an embodiment in cross section, respectively.
3 is a conceptual diagram illustrating a noise measurement method applied to noise level evaluation of an embodiment.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. However, implementations may be implemented in many different forms and are not limited to the embodiments described herein. Like reference numerals have been assigned to like parts throughout the specification.

In this specification, the term "combination of these" included in the expression of the Markush form means a mixture or combination of one or more selected from the group consisting of the components described in the expression of the Markush form, It means including one or more selected from the group consisting of.

In this specification, description of "A and/or B" means "A, B, or A and B".

Throughout this specification, terms such as "first" and "second" are used to distinguish the same terms from each other. Also, expressions in the singular number include plural expressions unless the context clearly dictates otherwise.

In this specification, ppm described without special mention is based on weight.

The drawings may be presented with exaggerated or omitted configurations for the purpose of explanation, and thus the scope of rights of the embodiments is not limited and interpreted.

As a representative biodegradable polymer, polylactic acid resin is attracting attention as a film material to replace the existing petroleum-based polyester film. However, the film to which the polylactic acid resin is applied generates a relatively loud crackling sound when used, which is pointed out as a disadvantage that prevents the film from being used as a packaging material. In particular, when a film containing polylactic acid resin is applied to a food packaging material close to life, such as a cookie bag or a bread bag, this rustling sound may act as a noise that causes an unpleasant sensation to the user.

Noise is a social problem to the extent that it is called noise pollution, and it is an object that needs to be reduced. In addition, since consumers are reluctant to select products that generate unnecessarily loud noises, in order for biodegradable films to replace existing petrochemical-based films for the purpose of eco-friendliness, it is necessary to provide biodegradable films that do not generate unnecessary noise. It is important.

The inventors have made various attempts to manufacture a film with low noise generation while obtaining biodegradable properties, and as a result, embodiments are presented. The inventors reduce the rustling sound of the biodegradable polyester film through the embodiment, obtain a mechanical strength of a certain level or more, confirm that it is excellent for use as a packaging material such as food, and propose an embodiment.

1, 2a and 2b are conceptual diagrams illustrating an example of a polyester film according to an embodiment in cross section, and FIG. 3 is a conceptual diagram illustrating a noise measurement method applied to noise level evaluation of the embodiment. Hereinafter, an embodiment will be described in detail with reference to FIGS. 1 to 3 .

A polyester film 100 according to an embodiment includes a first layer 52 containing lactic acid residues; and a second layer 54 including a terephthalate residue and an adipic acid residue; a laminate 50 alternately stacked (see FIG. 1).

A polyester film 100 according to another embodiment includes the laminate 50 described above and a skin layer 70 disposed on one or both surfaces of the laminate (see FIGS. 2A and 2B).

laminate

The laminate 50 is a laminate in which a first layer and a second layer containing distinct polymer resins are alternately laminated.

The first layer 52 includes residues of lactic acid.

The first layer 52 may include a polylactic acid based resin (PLA based resin).

Unlike petroleum-based resins, polylactic acid-based resins are based on biomass and help to reduce carbon dioxide emissions. In addition, as it is biodegradable, it is environmentally friendly because it is decomposed faster than petroleum-based resin by moisture and microorganisms during landfill.

The polylactic acid-based resin may be included in an amount of 50% by weight or more, 80% by weight or more, 85% by weight or more, 90% by weight or more, 93% by weight or more, 95% by weight or more, or 97% by weight or more based on the total amount of the first layer. can be included as In addition, it may be included in 99.9% by weight or less, or 99% by weight or less.

The polylactic acid-based resin may include L-lactic acid residues, D-lactic acid residues, D, L-lactic acid residues, or combinations thereof.

The content of L-lactic acid residues in the polylactic acid-based resin may be 80 mol% or more, 83 mol% or more, 85 mol% or more, 88 mol% or more, 90 mol% or more, or 92 mol% based on the total polylactic acid-based resin. may be ideal In addition, the content of L-lactic acid may be 99 mol% or less, 97 mol% or less, 95 mol% or less, or 93 mol% or less. In this case, the heat resistance properties of the film can be further improved.

The content of D-lactic acid residues in the polylactic acid-based resin may be greater than 0 mol%, 0.5 mol% or more, or 1 mol% or more based on the total amount of the polylactic acid-based resin. Also, the content of D-lactic acid may be 5 mol% or less, or 3 mol% or less. In this case, the stretching processability of the film can be further improved.

The polylactic acid-based resin may have a weight average molecular weight (Mw) of 100,000 to 1,000,000 g/mol, such as 100,000 to 800,000 g/mol, 100,000 to 500,000 g/mol, or 100,000 to 300,000 g/mol. The weight average molecular weight (Mw) may be measured by gel permeation chromatography (GPC). When the weight average molecular weight (Mw) of the polylactic acid-based resin satisfies the above range, it can help to improve mechanical properties of the film.

The first layer 52 may further include hydroxyalkanoate moieties.

The hydroxyalkanoate moiety may be derived from a polyhydroxyalkanoates resin (PHA resin).

The first layer 52 may include a polylactic acid-based resin and a polyhydroxyalkanoates resin.

Polyhydroxyalkanoates resins are semi-crystalline thermoplastic polyester compounds that can be produced by chemical synthesis or microorganisms (bacteria or algae), and are used in the manufacture of biodegradable plastics.

Polyhydroxyalkanoates resins include poly[3-hydroxybutyrate](P3-HB); poly[4-hydroxybutyrate] (P4-HB); poly[3-hydroxyvalerate] (PHV); poly[3-hydroxybutyrate]-co-poly[3-hydroxyvalerate] (PHBV); poly[3-poly[3-hydroxyhexanoate] (PHC); poly[3-hydroxyheptanoate] (PHH); poly[3-hydroxyoctanoate] (PHO); poly[3-hydroxynonanoate] (PHN); poly[3-hydroxydecanoate] (PHD); poly[3-hydroxydodecanoate] (PHDD); and poly[3-hydroxy tetradecanoate] (PHTD).

Specifically, the polyhydroxyalkanoates resin is composed of 3-hydroxybutyrate residues (3-hydroxybutyrate residues, 3HB residues), 4-hydroxybutyrate residues (4-hydroxybutyrate residues, 4HB residues), and combinations thereof. It may contain any one selected from the group.

The polyhydroxyalkanoates resin may contain 50 mol% or more, 55 mol% or more, or 60 mol% or more of 3HB residues based on the total polyhydroxyalkanoates resin. 100 mol% or less of the residue may be included, 80 mol% or less, or 70 mol% or less may be included.

The polyhydroxyalkanoates resin may contain 50 mol% or less, 45 mol% or less, or 40 mol% or less of 4HB residues based on the total polyhydroxyalkanoates resin. The residue may be included in an amount of 0 mol% or more, 20 mol% or more, or 30 mol% or more.

The polyhydroxyalkanoates resin may include both 4HB residues and 3HB residues, and may include 30 mol% to 35 mol% of 4HB residues based on the total amount of the polyhydroxyalkanoates resin. In this case, the crystallinity of the film may be adjusted to help improve mechanical properties.

The first layer 52 may be prepared by applying a blended resin of the polylactic acid-based resin and the polyhydroxyalkanoates resin. Through this, it can contribute to imparting characteristics such as biodegradability and appropriate mechanical properties to the polyester film at least a certain level.

The hydroxyalkanoate residue included in the first layer 52 may be 1 to 7 parts by weight or 2 to 6 parts by weight based on 100 parts by weight of the lactic acid residue. When a resin having the above residues is applied in this range, it can impart strength to the film, help control the crystallinity in the biaxial stretching process, and provide a film with reduced noise level overall by adjusting the physical properties of the relatively hard first layer. can do.

The resin applied to the first layer 52 may have a melt viscosity of 5,000 P or more, or 7,000 P or more, or 14,000 P or less, or 12,000 P or less at 210 °C. In this case, it is possible to have stable workability when manufacturing a laminate by an extrusion method.

The first layer 52 may further include inorganic particles. The inorganic particles may illustratively serve as an anti-blogging agent, but are not limited thereto.

Examples of inorganic particles applied to the first layer include silica (SiO ₂ ), calcium carbonate (CaCO ₃ ), indium tin oxide (ITO), and aluminum hydroxide (Al ₂ (OH) ₃ ). Zinc oxide (ZnO), titanium dioxide (TiO ₂ ), or barium sulfate (BaSO ₄ ) may be included.

The inorganic particles may have a D ₅₀ of 1 μm or more, or 1.5 μm or more. The D ₅₀ may be 3 μm or less or 2 μm or less.

The inorganic particles may be included in the first layer or the skin layer in an amount of 2,000 ppm or less and 1,500 ppm or less based on the entirety of each layer. When the inorganic particles are included in the skin layer, it may serve as an antiblocking agent.

In addition, when the first layer includes inorganic particles containing calcium carbonate, it may help to reduce noise generation of the polyester film.

The first layer 52 may further include a conventional antistatic agent, an antistatic agent, an antioxidant, a heat stabilizer, a sunscreen, an antiblocking agent, or a combination thereof as needed.

The second layer 54 includes terephthalate residues and adipic acid residues.

The second layer 54 has an aliphatic-aromatic co-polyester-based resin as a main component, and specifically includes an adipic acid residue and a terephthalate residue.

The aliphatic-aromatic co-polyester-based resin may include an aliphatic dicarboxylic acid residue of adipic acid and an aromatic dicarboxylic acid residue of terephthalic acid, and may further include a glycol residue.

The aliphatic dicarboxylic acid may further include, for example, succinic acid, sebacic acid, glutalic acid, malonic acid, oxalic acid, azelaic acid, or nonanedicarboxylic acid.

The aromatic dicarboxylic acid may further include, for example, isophthalic acid, naphthalene-2,6-dicarboxylic acid, diphenylsulfonic acid dicarboxylic acid, diphenylether dicarboxylic acid, diphenoxyethane dicarboxylic acid, or cyclohexane dicarboxylic acid. there is.

The glycol residue is ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, propylene glycol, neopentyl glycol, 2-methyl-1,3-propane It may be any one residue selected from alkylene glycols such as diol and diethylene glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, polyethylene glycol, and mixtures thereof.

The resin included in the second layer 54 may have an aliphatic component content of 30 mol% or more, 40 mol% or more, 45 mol% or more, or 50 mol% or more based on the total acid component. In addition, the aliphatic component may be 80 mol% or less, 70 mol% or less, or 60 mol% or less based on the total acid component. In this case, the biodegradability of the polyester film can be further improved.

The resin applied to the second layer 54 may be illustratively a polybutylene adipate terephthalate (PBAT) resin, and in this case, it may help to reduce noise and improve workability in the film manufacturing process.

The resin applied to the second layer 54 may have a melt viscosity of 3,000 P or more, or 4,000 P or more, and 9,000 P or less, or 7,000 P or less, at 210 °C. In this case, it is possible to have stable workability when manufacturing a laminate by an extrusion method.

The aliphatic-aromatic copolymer polyester-based resin has a weight average molecular weight (Mw) of, for example, 50,000 to 400,000 g/mol, for example 50,000 to 300,000 g/mol, for example 50,000 to 200,000 g/mol, or for example 50,000 to 100,000 g/mol can The weight average molecular weight (Mw) may be measured by gel permeation chromatography (GPC). In this case, it may have excellent compatibility with the resin applied to the first layer and excellent processability.

The second layer 54 may further include a conventional antistatic agent, an antistatic agent, an antioxidant, a heat stabilizer, a sunscreen, an antiblocking agent, or a combination thereof as needed.

The second layer 54 has a softer character compared to the first layer 52 .

The relatively hard first layer and the relatively soft second layer are alternately laminated to form the laminate 50 . The mechanical properties of the laminate as a whole can be maintained at a certain level or higher by the first layer, and noise generation in the process of using the film can be reduced due to the interaction between the first layer and the second layer. In particular, compared to the polylactic acid film, it is possible to provide a film with significantly reduced equivalent noise level and low-frequency noise level.

In addition, due to the multi-layer lamination of the laminate, the optical properties of the polyester film can also be improved. It has this lowering characteristic. Accordingly, embodiments can provide a film having excellent light transmittance in visible light.

The total number of layers of the laminate 50 may be 4 or more, 6 or more, 10 or more, 30 or more, 34 or more, or 36 or more. The laminate may have 424 layers or less, 324 layers or less, or 224 layers or less. When the total number of layers of the laminate is difficult to distinguish between the first layer of the laminate and the adjacent skin layers by applying the same resin as the first layer resin to the skin layer to be described later, the first layer of the laminate is considered to exist. It is based on the number of floors determined by assumption.

In the laminate 50, the first layer 52 and the second layer 54 are alternately laminated in a multi-layer structure, thereby providing a multi-layer polyester film with improved noise level while maintaining the mechanical strength of the polyester film at an appropriate level or higher. can provide

In the laminate, 36 or more layers of the first layer and the second layer may be alternately laminated, or 36 to 144 layers may be alternately laminated. In this case, noise generated when the polyester film is applied to a general bag such as a snack bag can be substantially reduced.

In the laminate 50, the average thickness ratio of the first layer 52 and the second layer 54 may be 1:0.2 to 1.5. An average thickness ratio of the first layer and the second layer may be 1:0.3 to 1.3. When the average layer thickness ratio of the first layer and the second layer satisfies the above range, a noise reduction effect may be obtained while maintaining a film strength of an appropriate level or higher.

The laminate 50 can be substantially completely biodegraded after a certain period of time in an environment where microorganisms and moisture exist, and thus has environmentally friendly characteristics.

The laminate 50 may have an average equivalent noise level of 78 db or less in evaluation of film noise level in which rotation of 180 degrees is applied at 800 rpm for 30 seconds or more. The average equivalent noise level may be 77.5 dB or less, 76 dB or less, 74.5 dB or less, or 73 dB or less. The average equivalent noise level may be 72 dB or more.

The film noise level evaluation was measured using a noise analyzer (14). The sample film (or laminate) for measurement is cut to an A4 size, and the long end of the sample is held by a fixing part (12, example: jig) to the bar 10 placed in a box where external noise is blocked, and the bar is By rotating the film, noise is generated. The distance (d) between the film and the end where the measuring part of the noise analyzer is placed is about 10 cm. For the generation of noise, the noise level generated by rotating the bar 180 degrees at a speed of 800 RPM was measured, and the rotation continued for 30 seconds or more (see FIG. 3).

Illustratively, a film cut to A4 size is prepared in a box of 650 (W) * 450 (D) * 500 (H) mm made of polycarbonate, and a digital noise analyzer from Cirrus Research PIC (model name: CR- 162C) is placed (see Fig. 3). The noise analyzer is located about 10 cm away from the prepared film, holds both ends of the film with a jig, rotates it 180 degrees, rotates it at 800 RPM, and makes noise for more than 30 seconds to measure the noise. Data analysis is based on the application of the NoiseTools Software program. Through the program, it is possible to evaluate the noise level, equivalent noise level, etc. for 30 seconds at each specific frequency. Illustratively, the noise level and the equivalent noise level can be measured in the range of 31.5 Hz to 16,000 Hz.

The evaluation of the average equivalent noise level is based on a value measured at a thickness of the laminate or the polyester film selected from 15 μm to 30 μm.

The laminate 50 may have a noise level of 63 dB or less, 62 dB or less, 61 dB or less, or 60 dB or less at 250 Hz in the film noise level evaluation when the thickness of the laminate 50 is 16 μm. This means having a relatively low noise level at a frequency representing a bass sound.

The laminate 50 may have a noise level of 53 dB or less, 52 dB or less, 51 dB or less, or 50 dB or less at 500 Hz in the film noise level evaluation when the thickness of the laminate 50 is 16 μm. This means that the noise level of a relatively low-pitched part that people feel is noisy is low.

When the thickness of the laminate 50 is 16 μm, the film noise level may be 59 dB or less, 57 dB or less, 56 dB or less, or 55 dB or less at 1,000 HZ. This means that the noise level in a relatively low range is low.

When the thickness of the laminate 50 is 16 μm, the film noise level may be 67 dB or less, 66 dB or less, 65 dB or less, 64 dB or less, or 63.5 dB or less at 2,000 HZ. This is noise at a frequency that is generally perceived as high by humans, and means that the noise level is substantially reduced.

When the thickness of the laminate 50 is 16 μm, the film noise level may be 75 dB or less, 74 dB or less, 73 dB or less, 72 dB or less, or 71 dB or less at 4,000 Hz. This is a region in which noise at a frequency that is generally perceived as high by humans and the largest noise occurs in the film, which means that the noise level is substantially reduced.

When the thickness of the laminate 50 is 16 μm, it may be 72 dB or less, 71 dB or less, 70.5 dB or less, 70 dB or less, 69 dB or less, or 68 dB or less at 8,000 Hz. This means that the generation of relatively high-pitched noise is reduced.

When the thickness of the laminate 50 is 16 μm, it may be 63 dB or less, 62 dB or less, 60 dB or less, or 58 dB or less at 16,000 Hz. This means that the generation of high-pitched noise is reduced.

The laminate 50 may have a haze of 10% or less, 9% or less, or 8% or less. The haze may be 2% or more or 4% or more. This is a haze value sufficient to be applied as a packaging material with appropriate optical properties, and is particularly excellent compared to simple blending of a resin having a lactic acid residue and an aliphatic-aromatic co-polyester resin. When the above two resins are simply blended, the compatibility of both resins is not good, and the resin becomes cloudy. In embodiments, by applying the structure of a laminate, it is possible to suppress deterioration in optical properties caused by poor compatibility of both resins and to obtain excellent optical properties. The haze is based on a value measured using a Hazemeter (model name: SEP-H) of Nihon Semitsu Kogaku.

skin layer

The polyester film 100 of the embodiment may further include a skin layer 70 .

The skin layer 70 may be disposed on one side or the other side of the laminate (see FIG. 2A).

The skin layer 70 may be disposed on one side or the other side of the laminate (see FIG. 2B).

The resin of the first layer 52 may be applied to the skin layer 70 . The resin of the second layer 54 may be applied to the skin layer 70 . In this case, it is possible to further improve the manufacturing workability of the polyester film, and it is possible to impart biodegradable properties to the film as a whole.

The skin layer 70 can further improve mechanical properties and workability of the polyester film when the resin of the first layer is applied.

As described above, the skin layer 70 may include inorganic particles as in the first layer, and additives may be applied as needed.

The thickness of the skin layer 70 may be applied in a thickness ratio of 5 to 25 based on the thickness of the laminate 50 100 . The skin layer 70 may have a thickness of 0.8 μm or more, 1.2 μm or more, or 2 μm or more, and the upper limit of the thickness is not particularly limited.

If the skin layer is applied to both the upper and lower portions of the laminate, the thickness of the skin layer described above means the thickness of one skin layer.

When the skin layer 70 is applied to the polyester film 100, it is possible to provide a film having excellent surface strength and controlled tactility and slip resistance as a whole.

polyester film

The polyester film 100 of the embodiment may have an average equivalent noise level of 78 dB or less in evaluation of film noise level in which rotation of 180 degrees is applied at 800 rpm for 30 seconds or more. The average equivalent noise level may be 77.5 dB or less, 76 dB or less, 74.5 dB or less, or 73 dB or less. The average equivalent noise level may be 72 dB or more.

Illustratively, based on a thickness of about 25 μm, when all are measured using the same measurement conditions, the average equivalent noise level of a general polyester film based on a petroleum-based material is about 80.3 dB, that of a polyester film using a polylactide resin. The average equivalent noise levels differ by about 83 to 85 dB.

The average equivalent noise level of the embodiment substantially suppresses or reduces noise generation while applying biodegradable polymers such as polylactic acid resin. That is, embodiments can provide a biodegradable polyester film that suppresses noise more than a polyester film (based on petroleum-based materials) applied as a packaging material for a product or the like.

The evaluation of the average equivalent noise level or the evaluation of the noise level is based on a value measured at a thickness of the laminate or the polyester film selected from 10 μm to 30 μm.

The polyester film 100 of the embodiment may have a noise level of 63 dB or less, 62 dB or less, 61 dB or less, or 60 dB or less at 250 Hz in the film noise level evaluation. This means having a relatively low noise level at a frequency representing a bass sound.

The polyester film 100 of the embodiment may have a noise level of 53 dB or less, 52 dB or less, 51 dB or less, or 50 dB or less at 500 Hz in the film noise level evaluation. This means that the noise level of a relatively low-pitched part that people feel is noisy is low.

The polyester film 100 of the embodiment may be 59 dB or less, 57 dB or less, 56 dB or less, or 55 dB or less at 1,000 HZ in the film noise level evaluation. This means that the noise level in a relatively low range is low.

The polyester film 100 of the embodiment may be 67 dB or less, 66 dB or less, 65 dB or less, 64 dB or less, or 63.5 dB or less at 2,000 HZ in the film noise level evaluation. This is noise at a frequency that is generally perceived as high by humans, and means that the noise level is substantially reduced.

The polyester film 100 of the embodiment may be 75 dB or less, 74 dB or less, 73 dB or less, 72 dB or less, or 71 dB or less at 4,000 Hz in the film noise level evaluation. This is a region in which noise at a frequency that is generally perceived as high by humans and the largest noise occurs in the film, which means that the noise level is substantially reduced.

The polyester film 100 of the embodiment may be 72 dB or less, 71 dB or less, 70.5 dB or less, 70 dB or less, 69 dB or less, or 68 dB or less at 8,000 Hz. This means that the generation of relatively high-pitched noise is reduced.

The polyester film 100 of the embodiment may be 63 dB or less, 62 dB or less, 60 dB or less, or 58 dB or less at 16,000 Hz. This means that the generation of high-pitched noise is reduced.

The polyester film may have a haze of 10% or less. In addition, the polyester film may have a haze of 6.5% or more and 9.5% or less. In addition, the polyester film may have a haze of 7% or more and 9% or less. When it has the haze range as described above, transparency is secured and can be used for various applications requiring light transmission. The haze was measured using a Hazemeter (model name: SEP-H) of Nihon Semitsu Kogaku.

The polyester film 100 of the embodiment may have a Young's modulus of 280 kgf/mm2 or less. The Young's modulus is based on the measurement according to ASTM D882, and means the average Young's modulus, which is the average value of the MD direction, which is the longitudinal direction of the film, and the TD direction, which is the transverse direction of the film.

The Young's modulus may be 280 kgf/mm2 or less, 275 kgf/mm2 or less, 270 kgf/mm2 or less, 220 kgf/mm2 or less, 200 kgf/mm2 or less, or 160 kgf/mm2 or less. The Young's modulus may be 80 kgf/mm 2 or more, 100 kgf/mm 2 or more, 120 kgf/mm 2 or more, 125 kgf/mm 2 or more, or 150 kgf/mm 2 or more. The Young's modulus is one of the indicators of the flexibility of the polyester film, and it is sometimes treated as having little noise generation. don't However, it shows that the film has a more flexible property as a whole.

The polyester film 100 of the embodiment may have a tensile strength of 3 kgf/mm2 or more, 4 kgf/mm2 or more, 5 kgf/mm2 or more, or 7 kgf/mm2 or more, 17 kgf/mm2 or less, 15 kgf/mm2 or less. or less, or 12 kgf/mm2 or less. When the tensile strengths of the MD direction and the TD direction are different, the tensile strengths mean their average values. The polyester film may have a tensile strength suitable for application as a packaging material.

The polyester film 100 of the embodiment may have an elongation of 60% or more, 70% or more, or 75% or more, and may be 120% or less. When the elongation rates in the MD direction and the TD direction are different, the elongation rate means an average value thereof. The polyester film may have elongation properties suitable for application to packaging materials,

The polyester film 100 of the embodiment may have a heat shrinkage rate of 5% or less, 4% or less, or 3% or less. The heat shrinkage rate may be 0.5% or more. This means that the polyester film has dimensional stability of a certain level or higher, and the embodiment may have stable heat shrinkage characteristics.

The polyester film 100 of the embodiment may have a thickness of 1,000 μm or less, 800 μm or less, 600 μm or less, 400 μm or less, 200 μm or less, 100 μm or less, or 60 μm or less. The thickness may be 10 μm or more, or 15 μm or more. In this case, it may have a thickness suitable for application as a packaging material.

The polyester film 100 of the embodiment includes a first layer comprising lactic acid residues; and a second layer including a terephthalate residue and an adipic acid residue; wherein the polyester film 100 is rotated at 180 degrees at 800 rpm for 30 seconds or more to evaluate the film noise level. The noise level may be 80 dB or less, 77 dB or less, or 75 dB or less. At this time, the noise levels mean values measured at 250 Hz, 500 Hz, 1000 Hz, 2000 Hz, 4000 Hz, and 8000 Hz, respectively.

The polyester film 100 is generally low in noise of various frequencies ranging from low to high tones that people mainly recognize, so it is possible to provide a polyester film that is environmentally friendly and relatively quiet while having mechanical strength above a certain level.

Manufacturing method of polyester film

A method for producing a polyester film according to another embodiment includes preparing a composition, obtaining an unstretched sheet; and obtaining a polyester film.

The composition preparation step is a step of preparing a first resin composition containing lactic acid residues and a second resin composition containing terephthalate residues and adipic acid residues (hereinafter referred to as the first step).

Obtaining an unstretched sheet is a laminate in which a first layer including the first resin and a second layer including the second resin are alternately laminated by melt-extruding the first resin composition and the second resin composition, respectively. This is a step of obtaining an unstretched sheet containing a sieve (hereinafter referred to as a second step).

The step of obtaining a polyester film is a step of obtaining a polyester film by stretching and heat-setting the laminated sheets (hereinafter referred to as the third step).

A detailed description of the polyester film and the laminate is omitted because it overlaps with that described above.

The first resin composition may include the resin of the first layer described above, inorganic particles, additives, and the like. The second resin composition may include the resin of the second layer described above, additives, and the like.

The melt viscosities of the first layer resin and the second layer resin at 210 ° C are the same as those described above, and when a resin having such a melt viscosity is applied to the first resin composition and the second resin composition, a laminate is manufactured by applying an extrusion method. advantageous to do

The first resin composition and the second resin composition may be subjected to a step of removing silver moisture in the first step and/or the second step, and the moisture content is preferably 150 ppm or less.

In the second step, a conventional film stacking means such as a feed block may be applied. Illustratively, the film stacking unit may have a structure in which molten resin corresponding to the first layer and the second layer may be discharged in a laminated manner, and may further include a portion where the resin of the skin layer is discharged. When the first resin composition or the second resin composition is applied to the skin layer, workability may be further improved. It is possible to control the thickness ratio of each layer of the laminate and the thickness ratio of the skin layer in a manner such as controlling the discharge amount of the molten resin.

The thickness ratio and the like are the same as those described above, and the thickness of each layer can be controlled and applied in consideration of the stretching process described later.

In the second step, after melt extrusion, the unstretched sheet may be formed into a sheet by a process such as bringing the unstretched sheet into close contact with a cooling roll.

The third step includes stretching the sheet in machine and transverse directions. After the stretching, a heat setting step may be further included.

The stretching may be biaxial stretching or sequential biaxial stretching. Specifically, the stretching step of preheating at 50 ℃ to 80 ℃, followed by longitudinal stretching 2 to 4 times in the machine direction (MD) at 40 ℃ to 100 ℃ and 3 in the transverse direction (TD) at 50 ℃ to 150 ℃ It may be to stretch 6 times.

The heat setting step may be performed at 50 °C to 150 °C, 70 °C to 150 °C, 100 °C to 150 °C, or 110 °C to 140 °C.

Through the stretching and the heat setting, the polyester film can improve mechanical strength and improve dimensional stability while having a thin thickness.

packaging material

A packaging material according to another embodiment includes the polyester film described above. A detailed description of the polyester film is omitted because it overlaps with that described above.

Packaging materials, for example, disposable packaging materials, food packaging materials, etc. may be applied, the polyester film may be applied as it is, and aluminum foil, color layers, etc. may be further included and applied.

The packaging material is eco-friendly because a biodegradable resin is applied to reduce the problem of carbon dioxide generation and is almost completely biodegradable under specific conditions. In addition, while applying polylactic acid resin, which is being researched as an existing biodegradable film, the noise level is lowered, mechanical strength, etc. are maintained at a certain level or higher, and the haze value is secured at an appropriate level, so it is excellent in utilization as a packaging material.

Hereinafter, embodiments will be described in more detail through specific examples. The following examples are only examples to aid understanding of the implementation, and the scope of the present invention is not limited thereto.

1. Preparation of polyester films of Examples 1 and 2

For the first resin composition, based on 100 parts by weight of the first resin, 93.9 parts by weight of polylactic acid polymer, 6 parts by weight of polyhydroxyalkanoate polymer, and 0.1 part by weight of calcium carbonate were applied.

In the first resin, the polylactic acid-based polymer has a D-lactide content of about 1 to about 3 mol%, a melt viscosity of about 7,000 to about 12,000 P (poise) at 210 degrees Celsius, and a polyhydroxyalkanoate-based polymer has a 4HB content of 30 to 35 mol%, and calcium carbonate has a particle size of D50 = 1.5 μm.

The second resin has a melt viscosity of about 4000 to about 7,000 P (poise) at 210 degrees Celsius based on 100 parts by weight of the second resin, and a polybutylene adipate co with an aliphatic component content of 50 mol% among acid components A terephthalide resin was applied at 100 parts by weight.

The first resin was dried in a dehumidifying dryer at 60 degrees Celsius for 8 hours or more, and the second resin was dried in a dehumidifying dryer at 80 degrees Celsius for more than 2 hours to remove moisture.

Using two extruders and a multi-layer feed block alternately stacked with a preset number of layers, the first resin was melt-extruded with an extruder having a temperature of 210 degrees Celsius and the second resin with an extruder having a temperature of 210 degrees Celsius. The discharge amount ratio (volume) of the first resin and the second resin was applied at 70:30.

In the multi-layer feed block, the first resin composition was branched into 36 layers and the second resin composition was branched into 36 layers and then alternately laminated, and the first and second layers were laminated into 72 layers, respectively, and the outermost layers of the upper and lower surfaces were respectively A skin layer was positioned at about 10% of the total thickness, and a first resin composition was applied to the skin layer to have the same composition as the first layer. Then, after passing through a 780 mm die, it was brought into close contact with a cooling roll cooled to 20 degrees Celsius to obtain an unstretched multilayer sheet of 73 layers including the outermost layer (the portion adjacent to the skin layer and the first layer is treated as one layer).

After the unstretched multilayer sheet was stretched 3.0 times in the machine direction at 65 degrees Celsius and 4.0 times in the transverse direction at 85 degrees Celsius, heat setting was performed at a relaxation rate of 1% at 120 degrees Celsius to obtain a 20 μm biaxially stretched multilayer film (Example 1). manufactured.

Example 2 was prepared in the same manner as Example 1, but was prepared to have a thickness of 25 μm after stretching and heat setting.

2. Preparation of polyester films of Examples 3 to 4

In Example 3, the first resin composition and the second resin composition were applied in the same manner as above, but the discharge amount ratio (volume ratio) of the first resin composition and the second resin composition was applied at 50:50.

In the multi-layer feed block, the first resin composition was branched into 36 layers and the second resin composition was branched into 36 layers and then alternately laminated, and the first and second layers were laminated into 72 layers, respectively, and the outermost layers of the upper and lower surfaces were respectively The skin layer was positioned at about 8% of the total thickness, and the first resin composition was applied to the skin layer to have the same composition as the first layer.

Other procedures were applied in the same manner as in Example 1 to prepare a 20 μm biaxially stretched multilayer film (Example 1).

In Example 4, a 25 μm biaxially stretched multilayer film was prepared in the same manner as in Example 3.

In Example 5, in the multi-layer feed block, the first resin composition was branched into 15 layers and the second resin composition was branched into 15 layers and then alternately laminated, and the first and second layers were laminated into 30 layers, respectively, on the upper and lower surfaces. A skin layer was placed on the outermost layer of each, and a first resin composition was applied to the skin layer to have the same composition as the first layer. A total of 31 layers of film was prepared, and the thickness of the film was 20 μm.

3. Preparation of polyester films of Comparative Examples 1 to 4

Comparative Example 1 used a polylactic acid-based polymer having a D-lactide content of about 1% to about 3 mol% and a melt viscosity of about 7,000 to about 12,000 P at 210 degrees Celsius. Moisture was removed by drying for 6 hours at 80 degrees Celsius with a dehumidifying dryer. The resin of the first resin layer was melt-extruded with an extruder having a temperature of 210 degrees Celsius. After passing through a 780 mm die, it was adhered to a cooling roll cooled to 20 degrees Celsius to obtain a single-layer unstretched sheet. The obtained single-layer unstretched sheet was stretched 3.0 times in the machine direction at 65 degrees Celsius and 3.8 times in the transverse direction at 85 degrees Celsius, and then given a heat setting temperature of 120 degrees Celsius and a relaxation rate of about 1% to obtain a biaxially stretched single-layer film of about 20 μm. manufactured.

In Comparative Example 2, 80% by weight of the polylactic acid-based polymer used in Example 1 and 20% by weight of the second resin were blended and used, and blended in a twin-screw extruder at 200 degrees Celsius. After drying this in a dehumidifying dryer at 60 degrees Celsius for 8 hours, it was melt-extruded at about 210 degrees Celsius to prepare a 30 μm single-layer unstretched sheet. This unstretched sheet was applied as the film of Comparative Example 2.

In Comparative Example 3, after hand mixing 10% by weight of polyhydroxyalkanoate and 90% by weight of polylactic acid-based polymer used in the first resin, they were blended in a twin-screw extruder at 200 degrees Celsius, processed into chips, and processed into chips using a dehumidifying dryer at 60 degrees Celsius. dried for more than 8 hours. Thereafter, the melt was extruded with a single extruder at a temperature of 210 degrees Celsius, passed through a 780 mm die, and then adhered to a cooling roll cooled to 20 degrees Celsius to obtain a single-layer unstretched sheet. The obtained single-layer unstretched sheet was stretched 3.0 times in the machine direction at 65 degrees Celsius and 3.8 times in the transverse direction at 85 degrees Celsius, and then given a heat setting temperature of 120 degrees Celsius and a relaxation rate of about 1% to obtain a biaxially stretched multilayer film of about 20 μm. manufactured.

In Comparative Example 4, a polylactic acid-based polymer having a D-lactide content of about 1 to 3 mol% and a melt viscosity of about 7,000 to 12,000 P at 210 degrees Celsius as a resin for the first layer and a resin for the second layer at 210 degrees Celsius In , a PBAT resin having a melt viscosity of about 4000 to about 7,000 P and an aliphatic component content of 50 mol% among acid components was used. The resin of the first resin was dried in a dehumidifying dryer at 60 degrees Celsius for 8 hours or more, and the second resin was dried in a dehumidifying dryer at 80 degrees Celsius for more than 2 hours to remove moisture. Using two extruders and a multilayer feed block in which two layers are alternately laminated, the resin of the first resin was melt-extruded with an extruder having a temperature of 210 degrees Celsius and the resin of the second resin was melt-extruded with an extruder having a temperature of 210 degrees Celsius. The discharge amount ratio (volume ratio) of the first resin and the second resin was applied as 70:30. In the multi-layer feed block, the first resin branched into 36 layers and the second resin branched into 36 layers, and then the first resin and the second resin were alternately stacked, and the upper and lower outermost layers were divided into about 20% of the total thickness. 1 resin was placed. Thereafter, after passing through a 780mm die, it was brought into close contact with a cooling roll cooled at 20 degrees Celsius to obtain an unstretched multilayer sheet of 73 layers including the outermost layer (the portion in direct contact between the first layer and the skin layer is treated as one layer because there is no layer distinction). The obtained unstretched multilayer sheet was stretched 3.0 times in the machine direction at 65 degrees Celsius and 4.0 times in the transverse direction at 85 degrees Celsius, and then subjected to a heat setting temperature of 120 degrees Celsius and a relaxation rate of 1% to prepare a 20 μm biaxially stretched multilayer film. .

4. Evaluation of physical properties

Noise level evaluation of film

A film cut to A4 size (210 mm x 297 mm) was prepared in a box of 650 (W) * 450 (D) * 500 (H) mm made of polycarbonate, and a digital noise analyzer (model name of Cirrus Research PIC) was used. :CR-162C) was placed. The noise analyzer was placed about 10 cm away from the prepared film, held both ends of the film with a jig, and rotated 180 degrees at 800 RPM for more than 30 seconds to measure the noise. For the analysis of the data, the equivalent noise level and noise level mode for each frequency of the NoiseTools Software program were applied. Through the program, the noise level and equivalent noise level for 30 seconds at a specific frequency were evaluated, and the results are shown in the table below.

Evaluation of mechanical properties

After making a film specimen in accordance with ASTM D882, cut it into a length of 150 mm and a width of 15 mm, mount it so that the gap between chucks is 50 mm, and test the specimen at a tensile speed of 200 mm/min using a tensile tester, Instron 5566A. After the experiment, the value of the straight line slope from the start of measurement to the point of reaching 3% elongation was measured as Young's modulus (kgf/mm2).

The tensile strength was measured using the same equipment as the maximum strength at tension (kgf/mm ² ) and the elongation as the percentage (%) of the initial increase at the time of sample fracture.

haze

It was measured according to the ASTM D1003 standard using a Hazemeter (model name: SEP-H) of Nihon Semitsu Kogaku.

Each measurement result is summarized in Tables 1 and 2 below.

Example # Example 1 Example 2 Example 3 Example 4 Example 5 Film thickness (um) 20 25 20 25 20 number of skin layers 2 2 2 2 2 1st/2nd floor set number of floors 36 36 36 36 15 total number of layers 73 73 73 73 31 Furtherance
(wt%) PBAT 30 30 50 50 30 PLA 65.73 65.73 46.95 46.95 65.73 PHAs 4.2 4.2 3.0 3.0 4.2 inorganic particles ^* 0.07 0.07 0.05 0.05 0.07 noise level
(dB) 250Hz 60.7 62.7 59.8 60.9 60.5 500Hz 50.6 52.7 50 51.2 50.3 1000Hz 54.8 58.2 54.3 55.7 54.4 2000Hz 64.2 66.8 63.2 65.6 63.8 4000Hz 72.1 74.2 70.2 72.4 71.8 8000Hz 70.3 71.6 67.1 69.1 70.1 Equivalent noise level (dB) 75.1 77.1 72.9 75.2 75.1 Average tensile strength (kgf/mm ² ) 9.95 9.3 5.5 4.3 10.3 Average Elongation (%) 101.5 102.5 91.5 81 99 Average Young's modulus (kgf/mm ² ) 274 268 122 158 262 Haze (%) 7.5 8.9 6.9 7.6 9.3

* The inorganic particles in the composition are calcium carbonate.

Example # Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 reference example Film thickness (um) 20 30 20 20 PET 100% 20um film number of skin layers fault fault fault 2 1st/2nd floor set number of floors - - - 36 total number of layers One One One 73 Furtherance
(wt%) PBAT 0 20 - 30 PLA 99.9 80 90 69.93 PHAs 0 0 10 0 inorganic particles 0.1 - - 0.07 noise level
(dB) 250Hz 62.7 - 61 - 64 500Hz 52.8 - 51.1 - 53.7 1000Hz 59.1 - 56.1 - 59.0 2000Hz 69.1 - 65.8 - 67.1 4000Hz 78 - 73.8 - 73.8 8000Hz 77.3 - 82.2 - 71.7 Equivalent noise level (dB) 81.2 80 76.8 79.8 78 Average tensile strength (kgf/mm ² ) 15.25 4.2 15.1 10 27.5 Average Elongation (%) 134 293 111 110 136 Average Young's modulus (kgf/mm ² ) 384 173 339 288 397 Haze (%) 1.5 25 11.4 4 2.7

* Among the compositions, the inorganic particles of Comparative Example 1 and Comparative Example 4 are silica.

Comparative Example 1 was a film using PLA alone, and it was reconfirmed that it had an equivalent noise level of 80 dB or more and was somewhat noisy. The Young's modulus value was also relatively large, and the flexibility of the film was somewhat lowered.

Unlike Comparative Example 1, Comparative Example 2 is a film using a resin in which PLA is blended with PBAT, and the flexibility is improved, but the equivalent noise level is still maintained at 80 dB, so loud noise is generated and the Haze value is greatly increased. This is considered to be due to the poor usability of the two resins.

In Comparative Example 3, a film using a resin blended with PLA and PHA had a Young's modulus of 300 kgf/mm ² or more, which was somewhat lacking in flexibility, and had a high Haze value.

Unlike Comparative Example 3, Comparative Example 4 is a film using an alternating layered structure of PLA and PBAT without blending PHA with PLA, and has an advantage in terms of light transmittance due to a lower Haze value than other Comparative Examples. However, it still has a high equivalent noise level and Young's modulus.

In the case of the examples, the equivalent noise level of the film tended to be lowered, and it was confirmed that the Haze value was low.

In Examples 1 to 4, it was confirmed that each polyester film had an equivalent noise level of 80 dB or less, a Young's modulus of 300 kgf/mm ² or less, and a Haze of no more than 10%.

All of the resins of Examples and Comparative Examples were made of biodegradable resin, and improved utilization as packaging materials by reducing the degree of noise generation, which was a disadvantage of existing biodegradable resin films, along with biodegradable properties.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concept of the present invention defined in the following claims are also made according to the present invention. falls within the scope of the rights of

100: polyester film
50: laminate
52: first layer
54: second layer
70: skin layer
10: bar
12: fixing part
14: noise analyzer
d: distance

Claims (11)

A first layer comprising a polylactic acid-based resin and a polyhydroxyalkanoate resin; And a second layer containing a terephthalate residue and an adipic acid residue; a polyester film comprising a laminated body in which a laminate is alternately laminated,
The polylactic acid-based resin contains lactic acid residues,
The polyester film has an average equivalent noise level of 78 dB or less and a Young's modulus of 280 kgf / ㎟ or less in the evaluation of film noise level applied with rotation of 180 degrees at 800 rpm for 30 seconds or more.
According to claim 1,
When the thickness of the laminate is 16 μm, the polyester film has a noise level of 63 dB or less at 250 Hz in the film noise level evaluation.
According to claim 1,
The polyester film has a haze of 10% or less, a polyester film.
According to claim 1,
When the thickness of the laminate is 16 μm, the polyester film has a noise level of 53 dB or less at 500 Hz in the film noise level evaluation.
According to claim 1,
The laminate is a polyester film in which the first layer and the second layer are alternately laminated with 30 or more layers.
According to claim 1,
The polyhydroxyalkanoate resin further comprises a hydroxyalkanoate residue, a polyester film.
According to claim 6,
The first layer contains 1 to 7 parts by weight of the hydroxyalkanoate residue based on 100 parts by weight of the polylactic acid-based resin,
The second layer comprises a polybutylene adipate co terephthalide resin, a polyester film.
According to claim 1,
The ratio of the thickness of the first layer and the second layer is 1: 0.2 to 1.5, a polyester film.
According to claim 1,
The polyester film further comprises a skin layer,
The skin layer is disposed on one side and the other side of the laminate, respectively,
The skin layer may include a first resin containing lactic acid residue; And containing inorganic particles, a polyester film.
A first layer comprising a polylactic acid-based resin and a polyhydroxyalkanoate resin; And a second layer containing a terephthalate residue and an adipic acid residue; a polyester film comprising a laminated body in which a laminate is alternately laminated,
The polylactic acid-based resin contains lactic acid residues,
The polyester film has a noise level of 80 dB or less at 250 Hz, 500 Hz, 1000 Hz, 2000 Hz, 4000 Hz and 8000 Hz when the film noise level is evaluated by applying a rotation of 180 degrees at 800 rpm for more than 30 seconds, polyester film.
A packaging material comprising the polyester film according to claim 1 .